1. Field of the Invention
The present invention relates to a tubing expansion tool and to a method of expanding tubing. In particular, but not exclusively, the present invention relates to a tubing expansion tool including an expansion member which is movable between a first configuration and a larger expansion configuration, and to a corresponding method.
2. Description of the Related Art
In the oil and gas exploration and production industry, a borehole of an oil or gas well is traditionally formed by drilling a bore from a wellhead to a first depth, and lining the drilled bore with a metal casing. The annulus between the casing and the borehole wall is then sealed with cement. The borehole is then extended, by drilling a smaller diameter bore from the upper cased section to a second depth. A smaller diameter casing is then installed from the wellhead, extending through the larger diameter casing to the second depth, and the second casing is then also cemented. This procedure is repeated until the borehole has been cased to a desired depth.
There has been considerable research in recent years into the development of expandable downhole tubing. The types of tubing developed include solid walled tubing, slotted or otherwise perforated tubing and expandable tubing-based sand exclusion assemblies, such as that disclosed in International Patent Publication WO 97/17524 (Shell), and as is available under the Applicant's ESS Trademark.
The introduction of expandable tubing has required the development of specialised expansion tools, some of which exert relatively high levels of torque and/or linear force on the tubing during an expansion process. However, the high levels of applied torque and force can cause problems both during and after expansion, particularly in the region of connections between tubing sections. For example, undesired deformation of the tubing, such as buckling, can occur due to a limited ability of the tubing to withstand the high levels of applied torque/force.
In one example of an existing method of expanding tubing, the applicant's International patent publication no. WO 02/103150 discloses locating an expansion cone in tubing to be expanded and applying impulses to the tool, to drive the tool through the tubing and expand the tubing to a larger diameter.
It is amongst the objects of embodiments of the present invention to provide an improved tubing expansion tool and method of expanding tubing. It is a further object of embodiments of the present invention to reduce or eliminate torque experienced by expandable tubing during an expansion process, such as in the areas of connections between expandable tubing sections.